Tag: chemistry

Questions Related to chemistry

A holoenzyme contains apoenzyme and ____________ .

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

  1. isoenzyme

  2. cofactor

  3. inhibitor

  4. none of the above

Show answer
Correct Option: B
Explanation:

Holoenzyme = Apoenzyme+ Cofactor.

Apoenzyme:-An apoenzyme is an inactive enzyme, activation of the enzyme occurs upon binding of an organic or inorganic cofactor.
Cofactor:-A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's activity

For a given sample of water containing the following impurities
$Mg{ \left( H{ CO } _{ 3 } \right)  } _{ 2 }=73mg/L;\quad Ca{ \left( H{ CO } _{ 3 } \right)  } _{ 2 }=162mg/L;\quad Ca{ SO } _{ 4 }=136mg/L$
$Mg{ Cl } _{ 2 }=95mg/L;\quad Ca{ Cl } _{ 2 }=111mg/L;\quad NaCl=100mg/L$
Then the total hardness (temporary and permanent) of above water sample is

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

  1. $300ppm$

  2. $350ppm$

  3. $450ppm$

  4. $500ppm$

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Correct Option: A

The metal ions (charged particles) that are required for contraction of muscles in human beings and animals are ions of:

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

  1. calcium

  2. sodium

  3. potassium

  4. iron

Show answer
Correct Option: A
Explanation:

$Ca^{2+}$ ions are required for contraction of muscles in humans.

Which of the following metals is required as a cofactor by all enzymes utilizing ATP in phosphate transfer?

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

  1. K

  2. Ca

  3. Na

  4. Mg

Show answer
Correct Option: D
Explanation:

Mg binds to phosphate group in ATP thus making a complex that catalyses phosphate transfer. 

The main constituents of pearl are:

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

  1. ammonium sulphate and sodium carbonate

  2. aragonite are conchiolin

  3. calcium carbonate and magnesium carbonate

  4. calcium oxide and ammonium chloride

Show answer
Correct Option: B
Explanation:

The chief component of the nacre that constitutes the pearl is aragonite $(CaCO _3)$. Nacre also contains a small amount of conchiolin, a hornlike organic substance (albuminoid) that is the main constituent of the mollusk's outer shell.

Which of the following statements is/are false?

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

  1. The halides of beryllium are electron deficient and are polymeric with halogen bridges.

  2. $BeF _2$ is very soluble in water owing to high solvation energy of Be but fluorides of other alkaline earth metals are almost insoluble.

  3. CaO, SrO and BaO react exothermically with water forming soluble hydroxides.

  4. The bicarbonates of alkaline earth metals are only stable in solutions.

Show answer
Correct Option: A,B,C,D

Select correct statement(s).

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

  1. $Mg^{2+}$ ions are necessary for the activation of phosphate transfer enzymes.

  2. Mg is present in chlorophyll of green plants.

  3. Mg is present in chlorophyll used in photosynthesis in green plants.

  4. All the above are correct statements

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Correct Option: D

Chlorophyll, the green component of plants contains:

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements

  1. $Ca^{2+}$

  2. $Be^{2+}$

  3. $Mg^{2+}$

  4. $Ba^{2+}$

Show answer
Correct Option: C
Explanation:

In plants, $Mg^{2+}$ is present in chlorophyll which is a green pigment useful for photosynthesis. It absorbs sunlight.

Bones and teeth contain:

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements

  1. Calcium dihydrogen phosphate

  2. Apatite

  3. Calcium phosphide

  4. None of the above

Show answer
Correct Option: B
Explanation:

Bones and teeth contains Apatite which is a group of phosphate minerals and contains calcium. Its formula can be represented as $Ca _5(PO _4) _3(F,Cl,OH)$.

What is litmus?

hydrogen ion scale or the ph scale inorganic analysis chemical analysis and investigation practical work chemistry

  1. Water soluble mixture of different dyes.

  2. Mixture of metal and non-metal ions.

  3. Both $A$ and $B$

  4. None of the above

Show answer
Correct Option: A
Explanation:

Litmus is a water-soluble mixture of different dyes extracted from lichens. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity. Wet litmus paper can also be used to test for water-soluble gases that affect acidity or alkalinity; the gas dissolves in the water and the resulting solution colors the litmus paper. For instance, ammonia gas, which is alkaline, colors the red litmus paper blue.